P0457 Loose Fuel Cap

P0457 Loose Fuel Cap - The fuel level is recorded by the Powertrain Control Module (PCM) when the ignition key is turned off, and is compared to the fuel level at the next ignition key on cycle. If the PCM recognizes a 25% increase in fuel level, the Leak Test Monitor is initiated.

If the Large leak test fails it is determined that the Fuel Filler Cap is faulty or not installed properly, or the Capless Fuel Filler Assembly flap did not seal properly after fueling. A LOOSE GAS CAP message will be displayed on the cluster to inform the customer.

The Powertrain Control Module (PCM) detects a 25% increase in fuel level from the previous ignition on state. The Powertrain Control Module (PCM) initiates an intrusive test after a 25% fuel level increase and the ESIM switch either opened before the maximum calibrated time, or the ESIM switch did not close at all. Default action, loose gas cap light will illuminate.

Possible Causes

• Loose or missing fuel filler cap.
• Large evap system leak.

Diagnose DTC P0457 Loose Fuel Cap

1. Fuel filler cap/capless fuel filler visual inspection

Visually inspect for the following:

• Loose, missing, or damage fuel filler or seal.
• Damage locking tabs on the fuel filler cap and/or filler tube.
• Damage seal points on the fuel filler cap and/or filler tube.

If the vehicle is equipped with the capless fuel filler assembly, visually inspect the flap and seal for proper sealing.

Were any problems found?

YES, repair as necessary.

NO, perform the P0455 Evap system large leak diagnostic procedure.

Test complete for DTC P0457 Loose Fuel Cap.

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